Method for producing complex organomineral fertilizer

Abstract

FIELD: organomineral fertilizers. SUBSTANCE: method for obtaining a complex organomineral fertilizer. Method which consists of preparing a solution of liquid manure containing ammonium nitrogen and phosphate ions mixed with water in a ratio of 1:5 or 1:1, or a filtrate of liquid manure obtained by filtering through non-woven fiber, mechanically cleaning it and settling it, to obtain magnesium ammonium phosphate. The prepared aqueous solution or filtrate of liquid manure is fed into the reactor at a temperature of 20-25°C, sodium hydroxide or soda is added to maintain an alkaline environment in the reactor with a pH of 9-9.5 and mixed with a solution of pre-prepared magnesium chloride or magnesium sulfate obtained from carnallite chlorate sludge, in a ratio of phosphate ions and magnesium ions of 0.9-1.1:1-1.2. Chemical precipitation of magnesium ammonium phosphate is carried out in a reactor at room temperature with stirring, after which the resulting suspension, including humates, is separated into a stream with small and large sediment particles in a hydrocyclone. The filtered sediment of large particles of magnesium-ammonium phosphate with humates is sent for granulation.EFFECT: increase in the efficiency of using agricultural waste with the production of valuable organomineral fertilizer with humates.3 cl, 1 tbl, 5 ex

Description

[0001] Field of technology to which the invention relates

[0002] The invention relates to methods for treating wastewater by removing specific compounds, specifically, to methods for utilizing ammonium nitrogen and phosphate ions from industrial or domestic wastewater. It can be used in agro-industrial, agricultural, chemical, and municipal facilities as part of treatment facilities. The resulting organomineral fertilizer can be used in combination with other potassium and nitrogen fertilizers in plant growing to accelerate crop growth.

[0003] Technology Level

[0004] A method for purifying wastewater from ammonium ions is known (patent CN103848540 (A), IPC class C02F1 / 52, publication date 06 / 11 / 2014). The technology for extracting ammonium nitrogen from wastewater in the form of struvite. The method includes the following steps: introducing a solution containing magnesium ion and phosphate ion into wastewater, adjusting the pH by dosing an alkali solution, forming solid particles in a reactor and subsequent filtration of struvite, final treatment of wastewater in an anaerobic reactor and marketing the resulting struvite as a prolonged-release fertilizer, where magnesium chloride and sodium phosphate are used as salts containing magnesium ion and phosphate ion, respectively; the optimal molar ratio of magnesium to nitrogen and phosphorus is 1.2: 1: 0.8; The ammonium nitrogen concentration of the incoming wastewater stream is 210-1260 mg / L; the solution for adjusting the pH in the range of 8.0 to 9.0 is a sodium hydroxide solution with a concentration of 2 to 6 mol / L.The disadvantage of this method is the production of a finely dispersed, difficult to filter struvite precipitate and the use of expensive sodium phosphate to precipitate struvite from wastewater.

[0005] A device and method for extracting nitrogen and phosphorus from wastewater by crystallization in the form of magnesium ammonium phosphate are known (CN108057414 (A), IPC class C02F 101 / 10, 2017-12-19). The reactor of the present invention includes a reactor body, an aeration device, a wastewater tank, an alkali tank and a chemical tank; the device for extracting nitrogen and phosphorus from wastewater by crystallization of struvite in the present invention adds only magnesium salt to maintain a magnesium to phosphorus ratio of 1.38, an end point pH of 9, an aeration time of 20 min, an ammonium nitrogen removal rate of 24.08%, an inorganic phosphorus removal rate of 90.13%, and a struvite purity in the sediment of 89.14%. In the second cycle, with the addition of phosphorus salt and magnesium salt, the N:Mg:P ratio is controlled at 1:1.12:0.98, the final pH is 9, and the aeration time is 20 minutes. After the second cycle, the ammonia nitrogen removal rate is 93.63%, and the inorganic phosphorus removal rate is 90.02%.The purity is 87.19%. A disadvantage of this method is the two-cycle wastewater treatment, which significantly increases the treatment time—40 minutes for one reactor volume—and the use of an expensive reagent—phosphorus salt.

[0006] The closest method to the claimed method is the method for extracting magnesium ammonium phosphate from wastewater (RU2792126C1, IPC C02F 1 / 583, C02F 1 / 586, C02F2101 / 16, C05B 9 / 00, 28.12.2022) containing ammonium and phosphate ions. The process is implemented as follows: an adjusting solution - sodium or ammonium hydroxide - is introduced into a reactor filled with wastewater. This is necessary to stabilize the pH in the range of 8.0-9.0. After adjusting the pH, the resulting solution in the reactor is mixed with one of the reagents: a solution of bischofite (magnesium chloride hexahydrate) or a pre-prepared acidic extract of magnesium silicate hydrous. In the next step, one of the silicon-containing components is added to the mixture: crushed diatomite; silica (the residue from the leaching of magnesium silicate hydrous); and silica sol. The resulting suspension is separated into two streams: one containing fine and one containing coarse sediment particles.The fine precipitate is returned to the reactor, which promotes crystal coarsening. The final steps are filtration of the coarse magnesium ammonium phosphate precipitate and drainage of the purified water from the system. A disadvantage of this method is the use of expensive bischofite and an expensive acidic extract of serpentinite (magnesium silicate hydrous), which reflects the cost of its production for treatment facilities.

[0007] Disclosure of the essence of the invention

[0008] The technical result of the claimed method for producing a complex organomineral fertilizer is an increase in the efficiency of using wastewater from industrial and agricultural production.

[0009] The specified technical result of the method for producing a complex organomineral fertilizer is achieved due to the fact that in order to obtain magnesium ammonium phosphate, a solution of liquid manure containing ammonium nitrogen and phosphate ions mixed with water in a ratio of 1:5 or 1:1 is prepared, or a filtrate of liquid manure obtained by filtering through non-woven fiber, it is mechanically cleaned and settled, after which the finished aqueous solution or filtrate of liquid manure is fed into a reactor at a temperature of 20-25 ° C, sodium hydroxide or soda is added to maintain an alkaline environment in the reactor with a pH of 9-9.5, and mixed with a solution of pre-prepared magnesium chloride or magnesium sulfate obtained from carnallite chlorate sludge, in a ratio of phosphate ions and magnesium ions of 0.9-1.1: 1-1.2, In this case, the chemical precipitation of magnesium ammonium phosphate is carried out in a reactor at room temperature with stirring, after which the resulting suspension, including humates, is separated,onto a stream with small and large particles of sediment in a hydrocyclone, after which the filtered sediment of large particles of magnesium-ammonium phosphate with humates is sent for granulation, while, to obtain a solution of magnesium chloride or magnesium sulfate, the sludge of carnallite chlorates is treated with a solution of hydrochloric or sulfuric acid for 20-60 minutes with stirring until completely dissolved to obtain a solution of magnesium chloride MgCl2 or magnesium sulfate MgSO, 4, after which the pH is brought to 6-7 in order to prevent the release of hydrogen sulfide when mixed with an aqueous solution or filtrate of liquid manure, while small particles of magnesium ammonium phosphate are returned to the reactor with an aqueous solution or filtrate of liquid manure to enlarge the crystals, then the precipitated large particles of magnesium ammonium phosphate with humates are filtered and the purified water is removed.

[0010] Implementation of the invention

[0011] Various types of wastewater have negative environmental impacts during removal, accumulation, storage, and subsequent use. These pollutants include nitrogen and phosphorus, which are valuable nutrients for most plants.

[0012] Recently, the production of complex fertilizers has increasingly turned to alternative raw material sources, such as wastewater from agro-industrial fish processing plants and domestic wastewater treatment plants. This allows for waste recycling, avoiding the extraction of mineral components, whose reserves are limited. These waters contain significant amounts of ammonium nitrogen and phosphate ions, the concentration of which can reach 2000 mg / L, as is the case, for example, with agricultural slurry. Most ammonium compounds are water-soluble, while struvite (magnesium ammonium phosphate, magnesium ammonium orthophosphate) has limited solubility in water in neutral and alkaline environments and is not washed away by rainwater. Struvite is widely used as a wastewater treatment product and fertilizer in the United States, China, and Canada, but it is not produced or used in Russia.It should also be noted that existing developments and existing methods are characterized by high cost due to the introduction of additional magnesium ions into the process and the use of pure substances and reagents.

[0013] The claimed method for producing a complex organomineral fertilizer is implemented as follows: magnesium salts are obtained from industrial wastewater containing ammonium nitrogen and phosphate ions in the form of solutions of magnesium chloride or magnesium sulfate (acid extract), for example, from the sludge of carnallite chlorinators produced by AVISMA JSC, containing MgO=61.60% by weight, MgCl2=18.37% by weight, KCl=29.50% by weight, NaCl=12.20% by weight.

[0014] Hydrochloric acid or sulfuric acid extract of carnallite chlorinator sludge is obtained by mechanical activation, followed by treatment with a solution of hydrochloric or sulfuric acid for 20-60 minutes with stirring until complete dissolution to obtain a solution of magnesium chloride MgCl2 or magnesium sulfate MgSO4, followed by neutralization of the solution with sodium hydroxide or soda to a neutral pH value.

[0015] The dissolution of carnallite chlorinator sludge, unlike serpentinite in the prototype, occurs in a solution of hydrochloric or sulfuric acids without heating by more than 99%, which eliminates the formation of harmful fumes, reduces dissolution time and the requirement for preliminary grinding.

[0016] The resulting iron impurities are separated from the solution of magnesium salts by sedimentation by alkalizing the solution first to pH=3, and then to a pH close to neutral pH=6-7.

[0017] The use of acid extracts (hydrochloric acid or sulfuric acid) from carnallite chlorate sludge as a magnesium-containing reagent reduces the cost and metal intensity of magnesium ammonium phosphate production due to the large volumes of carnallite chlorate sludge dumps available at AVISMA JSC.

[0018] Using an extract from agricultural slurry as a raw material for obtaining organomineral fertilizer significantly reduces the consumption of sodium hydroxide or soda solution to adjust the pH to the alkaline side, since the pH of the slurry solution has a value close to pH = 7.5-8.

[0019] Humic acids, which are part of the slurry when alkalized and magnesium salt is added, precipitate together with magnesium ammonium phosphate and magnesium carbonate, helping to strengthen the fertilizer granules during granulation.

[0020] The particle size of the resulting sediment and the presence of humates, due to their lower solubility, affect the availability of nutrients and make it possible to reduce the need for future application of fertilizers for agricultural crops into the soil at the synthesis stage, and to reduce the costs of fuel and lubricants during the growing season.

[0021] The resulting organo-mineral fertilizer can be used in combination with other potassium and nitrogen fertilizers in a complex form when applied to open and closed soils, and the presence of humates and microelements from slurry increases its agronomic value.

[0022] An aqueous solution of liquid manure containing ammonium ions and phosphate ions, after mechanical cleaning and settling, is fed into a wastewater reactor at room temperature of about 20-25°C.

[0023] To maintain the alkaline environment of wastewater with a pH of 9-9.5, a correction solution in the form of sodium hydroxide or soda is added to the solution.

[0024] A corrected solution of liquid manure, simulating wastewater from agricultural enterprises, is mixed in a reactor with a solution of pre-prepared acid extract from the sludge of carnallite chlorinators in a ratio of phosphate ions and magnesium ions close to stoichiometric (0.9-1.1:1-1.2).

[0025] Experts are well aware, based on Pourbaix diagrams, that wastewater containing sulfur in the form of sulfides and mercaptans, found in livestock effluents, begins to release hydrogen sulfide when acidified with acidic solutions below pH 3. Therefore, a magnesium salt solution is first alkalized to a pH close to neutral (pH 6-7) and then mixed with a solution of wastewater (slurry from agricultural enterprises) to precipitate magnesium ammonium phosphate.

[0026] Chemical precipitation of magnesium ammonium phosphate is carried out in a reactor at room temperature with stirring, after which the resulting suspension, including humates, is separated into a stream with small and large sediment particles in a hydrocyclone.

[0027] Fine magnesium ammonium phosphate particles are returned to the wastewater reactor as slurry to coarsen the crystals. The precipitated magnesium ammonium phosphate and humates are then filtered, and the purified water is discharged. The filtered magnesium ammonium phosphate and humates precipitate is sent for granulation.

[0028] The resulting product in the form of a complex organomineral fertilizer has advantages not only from the agronomic point of view, but also from the point of view of certification.

[0029] The claimed method for obtaining a complex organomineral fertilizer is carried out as follows:

[0030] Example 1. A by-product of livestock farming—slurry from a cattle farm lagoon in the village of Lobanovo, Perm Krai—was used as a raw material source for magnesium ammonium phosphate. Analysis of ammonium nitrogen and phosphate ion content using a KAPEL-105M capillary electrophoresis system revealed the presence of 2529.5 mg / L of ammonium nitrogen and 628.7 mg / L of phosphate ions. Magnesium chloride hexahydrate, analytical grade, manufactured by Khimreaktivsnab, JSC, was used as the magnesium source.

[0031] To obtain a complex organomineral fertilizer in the form of magnesium ammonium phosphate, a beaker with a lid mounted on a magnetic stirrer was used. 500 ml of distilled water (1:5) was added to the beaker with 100 ml of slurry while stirring. The suspension was then allowed to settle, and 100 ml of the clarified liquid phase was collected. Next, 100 ml of the resulting solution was alkalized with a 100 g / L sodium hydroxide solution to a pH of 8.5. A prepared solution of magnesium chloride hexahydrate (analytical grade) manufactured by Khimreaktivsnab CJSC was gradually added at a concentration of 0.01% by weight until a precipitate of magnesium ammonium phosphate was suspended. During the process of introducing magnesium chloride solution into the clarified liquid phase of slurry, the pH of the mixture was adjusted in the range of pH = 9-9.5 units with sodium hydroxide solution.The resulting magnesium ammonium phosphate precipitate was then separated on a "White Lenta" filter, washed with 50 ml of distilled water, and dried at 60°C in a drying oven to constant weight. The mass of the organomineral fertilizer, in the form of magnesium ammonium phosphate precipitate, obtained using liquid manure and magnesium chloride solution, was 1.139 g. As a result, the purification rate of the original liquid manure solution was 96.95% by weight, based on the degree of phosphate ion precipitation.

[0032] After separating magnesium ammonium phosphate, the filtrate was analyzed to determine the residual content of cations and anions using the KAPEL-105M capillary electrophoresis system, the results of which are presented in Table 1.

[0033] Example 2. A by-product of livestock farming—slurry from a cattle farm lagoon in the village of Lobanovo, Perm Krai—was used as a source of ammonium nitrogen and phosphate ions to produce magnesium ammonium phosphate. Analysis of ammonium nitrogen and phosphate ions using a KAPEL-105M capillary electrophoresis system revealed the presence of 2529.5 mg / L of ammonium nitrogen and 628.7 mg / L of phosphate ions.

[0034] Magnesium chloride hexahydrate of analytical grade, manufactured by Khimreaktivsnab JSC, was used as a source of magnesium.

[0035] To obtain magnesium ammonium phosphate, a beaker with a lid mounted on a magnetic stirrer was used. 500 ml of distilled water (1:5) was added to the beaker with 100 ml of liquid manure while stirring. The suspension was then allowed to settle, and 500 ml of the clarified liquid phase was collected. Next, 50 ml of the resulting solution was alkalized with a 100 g / L sodium hydroxide solution to a pH of 8.5 units. A prepared solution of magnesium chloride obtained from carnallite chlorate sludge was gradually added at a concentration of 0.01% by weight until a precipitate suspension of magnesium ammonium phosphate was formed. During the addition of the spent electrolyte solution, the pH was adjusted to 9.0 units with a sodium hydroxide solution.

[0036] The resulting magnesium ammonium phosphate precipitate was then separated on a White Ribbon filter, washed with 50 ml of distilled water, and dried at 60°C in a drying oven to constant weight. The mass of the organomineral fertilizer, in the form of magnesium ammonium phosphate precipitate, obtained using slurry and magnesium chloride solution, was 0.287 g. As a result, the purification rate of the original slurry solution was 99.66% by weight, based on the degree of phosphate ion precipitation.

[0037] After separating magnesium ammonium phosphate, the filtrate was analyzed to determine the residual content of cations and anions using the KAPEL-105M capillary electrophoresis system, the results of which are presented in Table 1.

[0038] Example 3. A complex organomineral fertilizer was obtained using the technology given in examples 1-2, with the difference that the filtrate of liquid manure without dilution with water (i.e. liquid manure with a moisture content of more than 90%), obtained by filtering through non-woven fiber, was used as a source of ammonium nitrogen and phosphate ions.

[0039] To obtain magnesium ammonium phosphate, a beaker with a lid mounted on a magnetic stirrer was used.

[0040] A prepared solution of magnesium chloride, obtained from carnallite chlorate sludge, was gradually added to a beaker containing 12.5 ml of liquid manure, which had been alkalized with a 100 g / L sodium hydroxide solution to a pH of 8.5, at a concentration of 0.01% by weight, until a precipitate of magnesium ammonium phosphate was suspended. While adding the spent electrolyte solution, the pH was adjusted to 9.5 with a sodium hydroxide solution.

[0041] The resulting magnesium ammonium phosphate precipitate was then separated on a White Ribbon filter, washed with 50 ml of distilled water, and dried at 60°C in a drying oven to constant weight. The mass of the organomineral fertilizer, in the form of magnesium ammonium phosphate precipitate, obtained using undiluted slurry and magnesium chloride solution, was 0.688 g. As a result, the purification rate of the original slurry solution was 99.90% by weight, based on the degree of phosphate ion precipitation.

[0042] After separating magnesium ammonium phosphate, the filtrate was analyzed to determine the residual content of cations and anions using the KAPEL-105M capillary electrophoresis system, the results of which are presented in Table 1.

[0043] Example 4. A complex organomineral fertilizer was obtained using the technology given in examples 1-2, with the difference that liquid manure diluted in a 1:1 ratio with water was used as a source of ammonium nitrogen and phosphate ions, and a prepared hydrochloric acid extract from the sludge of carnallite chlorinators was used as a source of magnesium. For the production of magnesium salts, necessary for the chemical precipitation of magnesium-ammonium phosphate, an acid extract from the sludge of carnallite chlorinators manufactured by AVISMA JSC (Berezniki, Perm Krai) was used.

[0044] A beaker containing 8.196 g of pre-crushed carnallite chlorinator slurry was mixed with 23 ml of chemically pure hydrochloric acid. The mixture was stirred to dissolve the rock. Then, 50 ml of distilled water was added to initiate a chemical reaction to dissolve the electrolyte. After more than 99% of the electrolyte had dissolved by weight, the resulting solution was neutralized with a 100 g / L solution of chemically pure sodium hydroxide to a pH of ~7, close to the onset of magnesium hydroxide precipitation as a white precipitate. Iron hydroxide precipitated and was separated on "White Lenta" filter paper. The resulting magnesium chloride solution was used to precipitate magnesium ammonium phosphate.

[0045] To obtain magnesium ammonium phosphate, 10 ml of liquid manure was diluted with distilled water at a 1:1 ratio and filtered to remove suspended particles. The resulting solution had a pH of 7. A 100 g / L sodium hydroxide solution was then added to pH 8.5.

[0046] The resulting solution from the liquid manure was alkalized with a sodium hydroxide solution with a concentration of 100 g / l to a pH of 8.5 units, and hydrochloric acid extract obtained from the sludge of carnallite chlorinators was gradually added until a suspended sediment was formed in the form of magnesium ammonium phosphate.

[0047] During the addition of the carnallite chlorinator sludge solution, the pH was adjusted to 9-9.5 with sodium hydroxide solution. The resulting magnesium ammonium phosphate precipitate was then separated on a "White Ribbon" filter, washed with 50 ml of distilled water, and dried at 60°C in a drying oven until constant weight was reached. The resulting precipitate was then weighed.

[0048] The resulting filtrate was analyzed for cation and anion content using a KAPEL-105M capillary electrophoresis system. The mass of magnesium ammonium phosphate precipitate, obtained using manure slurry and hydrochloric acid extract from carnallite chlorinator sludge, was 1.337 g. As a result, the purification efficiency of the original manure slurry solution was 99.90% by weight, based on phosphate ion precipitation. The analysis results are presented in Table 1.

[0049] The result is a magnesium ammonium phosphate powder with humates, which can be granulated using known methods to produce commercial fertilizer.

[0050] Example 5. A complex organomineral fertilizer was obtained using the technology given in examples 1-2, with the difference that liquid manure diluted in a 1:1 ratio with water was used as a source of ammonium nitrogen and phosphate ions, and a prepared sulfuric acid extract from the sludge of carnallite chlorinators was used as a source of magnesium.

[0051] To obtain magnesium salt from the sulfuric acid extract of carnallite chlorinator sludge, necessary for the chemical precipitation of magnesium ammonium phosphate, carnallite chlorinator sludge produced by AVISMA JSC (Berezniki, Perm Krai) was used.

[0052] A beaker containing 8.185 g of pre-crushed carnallite chlorinator slurry was mixed with 12 ml of chemically pure sulfuric acid. The mixture was stirred to dissolve the rock. Then, 50 ml of distilled water was added to initiate a chemical reaction to dissolve the slurry. After more than 99% of the slurry had dissolved by weight, the resulting solution was neutralized with a 100 g / L solution of chemically pure sodium hydroxide to a pH of ~7, close to the onset of magnesium hydroxide precipitation as a white precipitate. Iron hydroxide precipitates (at a pH above 2.3), which is separated on "White Lenta" filter paper. The resulting magnesium chloride solution is used to precipitate magnesium ammonium phosphate.

[0053] To obtain magnesium ammonium phosphate, 10 ml of liquid manure was diluted with distilled water at a 1:1 ratio and filtered to remove suspended particles. The resulting solution had a pH of 7. A 100 g / L sodium hydroxide solution was then added to pH 8.5.

[0054] The resulting slurry solution was alkalized with a 100 g / L sodium hydroxide solution to a pH of 8.5. A prepared magnesium salt solution obtained from carnallite chlorinator sludge was gradually added until a precipitate of magnesium ammonium phosphate was suspended. During the addition of the carnallite chlorinator sludge solution, the pH was adjusted to 9-9.5 with sodium hydroxide. The resulting magnesium ammonium phosphate precipitate was then separated on a "White Lenta" filter, washed with 50 ml of distilled water, dried at 60°C in a drying oven to constant weight, and weighed. The resulting filtrate was analyzed for cation and anion content using a "KAPEL-105M" capillary electrophoresis system. The mass of magnesium ammonium phosphate precipitate obtained using magnesium chloride obtained from carnallite chlorinator sludge and liquid manure was 1.143 g.The initial slurry solution was purified to 99.90% by weight based on phosphate ion precipitation. The analysis results are presented in Table 1.

[0055] The result is a magnesium ammonium phosphate powder with humates, which can be granulated using known methods to produce commercial fertilizer.

[0056] Table 1

[0057] Weight composition of magnesium-ammonium phosphate elements with humates and effluents obtained using magnesium chloride and acid extracts from the sludge of carnallite chlorinators of JSC AVISMA and slurry from a cattle barn

[0058] Experimental option Input content, mg / l Amount of added Mg2+, mg / l pH of precipitation Output content, mg / l Mass of magnesium ammonium phosphate with humates, g Degree of extraction of phosphate ions, % by weight. NH4+ Mg2+ PO43- NH4+ Mg2+ PO43- Ex. 1 Liquid manure (1:5) + magnesium chloride solution 2529,5 164,85 628,7 358,9 9,5 9,8 20,7 77,1 1,139 96,95 Ex. 2 Liquid manure (1:5) + magnesium chloride 2529,5 164,85 628,7 370,9 9,0 24,3 5,6 8,6 0,287 99,66 Ex. 3 Liquid manure (1:0) + magnesium chloride solution 2529,5 164,85 628,7 2105,59 9,5 81,27 361,83 <2,5 0,688 99,90 Ex.4 Liquid manure (1:1) + hydrochloric acid extract from carnallite chlorinators sludge 2529,5 164,85 628,7 3453,46 9,0 158,13 2244,5 <2,5 1,337 99,9 Ex. 5 Liquid manure (1:1) + sulfuric acid extract from carnallite chlorinators sludge 2529,5 164,85 628,7 3448,8 9,0 95,43 3234,5 <2,5 1,143 99,9

[0059] The results presented in Examples 1-5 of Table 1 demonstrate that the addition of magnesium salts in the form of magnesium chloride or magnesium sulfate during alkalization to a pH of 9-9.5 enables the effective precipitation of phosphate ions with a recovery rate of over 96% by weight in the form of magnesium ammonium phosphate along with humates from a solution of cowshed slurry-based wastewater. When using acidic extracts of magnesium salts in the form of magnesium chloride or sulfate, obtained from the sludge of carnallite chlorinators manufactured by AVISMA JSC, the recovery rate of phosphate ions reaches 99.9% by weight of the original content, producing a valuable organomineral fertilizer with humates, confirming the stated technical result.

[0060] The use of complex fertilizers containing magnesium ensures early fruiting, accelerated growth, and a noticeable improvement in the flavor of agricultural crops. Modification of the release of nutrients in known complex fertilizers is typically achieved through granulation with a binder, the addition of poorly soluble compounds such as calcium sulfate or phosphate, and the addition of amorphous silica or zeolites, which prevent the dissolution of the target components.

[0061] The fertilizer produced by the proposed method ensures controlled release of nutrients thanks to the presence of humates and magnesium carbonate in the sludge. Humates are known to promote moderate nutrient release, retain micronutrients from slurry, and, upon drying, form a densely packed structure with the sludge. This ensures gradual dissolution of magnesium ammonium phosphate and micronutrients when the fertilizer is applied to the soil.

[0062] The compositional features of magnesium ammonium phosphate—moderate solubility and the presence of crystallization water—provide two important agronomic benefits: a stable, measured supply of nutrients to plants throughout the growing season; and the ability to retain soil moisture, which is especially valuable during drought conditions. Magnesium, an element found in chlorophyll, promotes active absorption of sunlight and is responsible for managing the water-holding capacity of plants during both dry and rainy periods. During drought, it prevents evaporation, and during rainy periods, it prevents plant rot. Humic substances, such as humic acids and humin, form stable complexes with the microelements found in livestock waste.

[0063] The presence of finely dispersed magnesium ammonium phosphate seed at the chemical precipitation stage creates conditions for heterogeneous crystallization, leading to the formation of a coarsely dispersed sediment with improved filtration characteristics.

[0064] The transition to the chemical precipitation method for extracting magnesium ammonium phosphate provides significant energy savings: it eliminates the need for energy-intensive vacuum evaporation units, which are currently used in the production of monoammonium phosphate and diammonium phosphate (ammophos).

[0065] The use of acid extracts (hydrochloric or sulfuric acid) from carnallite chlorinator sludge as a magnesium-containing reagent reduces the cost and metal intensity of magnesium ammonium phosphate production, thanks to the large volumes of carnallite chlorinator sludge dumps available at AVISMA JSC.

Claims

1. A method for producing a complex organomineral fertilizer, characterized in that in order to obtain magnesium-ammonium phosphate, a solution of liquid manure containing ammonium nitrogen and phosphate ions mixed with water in a ratio of 1:5 or 1:1 is prepared, or a filtrate of liquid manure obtained by filtering through non-woven fiber, it is mechanically cleaned and settled, after which the finished aqueous solution or filtrate of liquid manure is fed into a reactor at a temperature of 20-25 ° C, sodium hydroxide or soda is added to maintain an alkaline environment in the reactor with a pH of 9-9.5 and mixed with a solution of pre-prepared magnesium chloride or magnesium sulfate obtained from carnallite chlorate sludge, in a ratio of phosphate ions and magnesium ions of 0.9-1.1: 1-1.2, while chemical precipitation of magnesium-ammonium phosphate is carried out in a reactor at room temperature with stirring, after which the resulting suspension, including humates, is separated,onto a stream with small and large particles of sediment in a hydrocyclone, after which the filtered sediment of large particles of magnesium-ammonium phosphate with humates is sent for granulation.

2. The method according to paragraph 1, characterized in that in order to obtain a solution of magnesium chloride or magnesium sulfate, the sludge of carnallite chlorates is treated with a solution of hydrochloric or sulfuric acid for 20-60 minutes with stirring until completely dissolved to obtain a solution of magnesium chloride MgCl2 or magnesium sulfate MgSO4, after which it is brought to a pH of 6-7 in order to prevent the release of hydrogen sulfide when mixed with an aqueous solution or filtrate of liquid manure.

3. The method according to paragraph 1, characterized in that small particles of magnesium ammonium phosphate are returned to the reactor with an aqueous solution or filtrate of liquid manure to enlarge the crystals, then the precipitated large particles of magnesium ammonium phosphate with humates are filtered and the purified water is removed.